Circuit breaker or overload control



Ap 1950 E. w. RICKMEYER 2,505,689

CIRCUIT BREAKER 0R OVERLOAD CONTROL Filed March 5, 1945 4 Sheets-Sheet 2 fig p v 5 5 Z7 5 Z4 47 5 .55 i .5] f 44 6 i;

49 Bl-MfTflZl/C' spmsmzuc 5Z- April 1950 E. w. RICKMEYER 2,505,689

CIRCUIT BREAKER OR OVERLOAD CONTROL Filed March 5, 1945 4 Sheets-Sheet 5 y I 6 Q o o 4 z/az/ pril 25, 1950 E. w. RECKMEYER 255,39

(JIRCUIT BREAKER 0R OVERLOAD CONTRQL Filed March 5, 1945 4, Sheets-Sheet 4 Patented as. 1950 amuse CIRCUIT BREAKER R OVER-LOAD CONTROL Ernst Walter Rickmeyer, Eimhurst, Ili., assign'or to JeiIerson Electric Company, Bellwood, 111., a corporation of Illinois Application March 5, 1945, Serial N0. 580,979

Claims.

This invention relates to an improved motor controlled device, and in particular to one embodying a thermally operated circuit breaker to prevent overloads.

This invention is particularl useful in connection with motors which have a separate starting winding, although it is obvious that it is applicable to other types of motor circuits.

It is an object 01' this invention to provide a common thermally operated circuit breaker for the protection of both the starting winding and running winding of an electric motor. Heretolore such a common circuit breaker has not been generally employed for the reason that the current drawn by the starting winding is sumciently great as to cause operation of the circuit breaker.

- A further object of this invention is to provide an improved circuit breaker having a delayed action so that it can carry a heavier load for a short period. such as the load imposed on it by the cutting in of a, starting winding, but which circuit breaker otherwise affords satisfactory protection for the motor when drawing currents less than that required for the cut-in of the starting winding, or the like.

With reference now to the drawings in which like reference numerals designate like parts:

' Fig. l is a plan view of a preferred embodiment of this invention;

Fig. 2 is a front elevation thereof;

Fig. 3 is a rear elevation thereof;

Fig. 4 is an enlarged detail of a portion of Fig. 1, showing the parts in a changed position; 7

Fig. 5 is a view similar to Fig. 4, but showing a still further change in the position of the parts;

Fig. 6 is a diagrammatic representation of the I invention as applied to a motor having a separate starting winding;

Fig. 7 is a section along line 1-1 of Fig. 2;

Fig. 8 is a section along line 8-4 of Fig. 2;

Has. 9 and 10 show a modified form of invention;

Figs. 11 and 12 show a further modification thereof; and

Fig. 13 is a detailed view of the heating element shown in P18. 11.

With reference now to Figs. 1 and 3, the reference numeral l0 designates generally a base on which is disposed a relay coil H, the latter being mounted at one end of a strip II, the strip being secured to the base. The strip i2 also includes a binding ost l3, to which a conductor it may be attached. The coil ii is insulated from the strip i2.

pends downwardly from the armature I8 into juxtaposition with a contact mounted on a plate 2 l.

The coil II is adapted to be connected into the motor circuit as hereinafter pointed out, and it will be seen that when the conditions are such that the motor draws a heavy current, the relay will be actuated to close a circuit through contacts l9 and 20. These contacts are connected into the circuit of the starting winding, as will be pointed out later in connection with Fig. 6.

The plate 2|, which is secured to base I0. carries a bent-up portion 23 having horizontally projecting ears 24 to which a, bimetallic strip 25 is staked. An adjusting screw 26 takes into the bent-up portion 23 to regulate the tension of the bimetallic strip 25. Another bracket 28 formed on plate 2| carries an adjustable contact point 21 in the form of a screw by which the throw of the bimetallic strip 25 may be controlled.

A bracket 30 is secured to the base in and carries a binding post 31 for conductor 32. A bimetallic U-shaped strip 33 having an upper terminal 34 and a. lower terminal 35, is secured to the bracket 30, and is separated therefrom by an insulating block 31. A resilient contact strip 36 is disposed intermediate the upper and lower arms of the U-shaped strip 33, and overlies the 7 upper terminal 34 so as to be in circuit therewith. A further insulating block 38 is disposed at the rear side of the bracket 30, and an L-shaped member 39 serves as a washer to receive screws .40 and 4| which hold the assembly together.

40 It will be noted that in Fig. 7 the bracket 30 is provided with apertures which clear the screws 40 and M, so that the upper terminal 34 and the contact strips 36 will be insulated from the bracket 30. Screws 42 and 43 pass through the 46, lower terminal 35 and the U-shaped strip 33 and take into the bracket 30.

It will be seen therefore that the resilient contact strip 36, the upper terminal 34, the main portion of the bimetallic U-shaped strip 33, the

50 lower terminal 35, the bracket 30 and the conductor 32 are all in series with each other.

The contact strip 36 carries the contact point 44 which cooperates with an oppositely disposed contact point 45 on the bimetallic strip 25. Thus A bracket i8 is mounted on strip i2, and in II when the armature I8 is in attracted position,

the circuit will be closed between conductors l4 and 32, and the current passes through twosets of bimetallic elements which are in series with each other, namely the strip 25 and the strip 33.

A spring 48 is disposed between the free end of the resilient contact strip 36 and the closed end of the bimetallic U-shaped strip 33. The parts are insulated from each other at this point by means of an insulating washer 41 which can be suitably secured to the bimetallic U-shaped strip 33, as by being slipped over a projection thereon. Thus it will be seen that there is an overcenter action between the bimetallio strip 33 and the contact strip 35.

A bracket 49 having an adjusting screw 50 limits the throw of the resilient contact strip 36 in a direction away from contact with the bimetallic strip 25.

The relay coil II is connected in series with a binding post 52 and conductor 53 by means of a lead The other end of the coil II is connected in series with the plate 2! by means of a lead 54.

Reference to Fig. 6 will indicate the manner in which the control device may be connected into a motor circuit. One terminal of a motor 51 is connected to one power line 55, and the other terminal of the motor 5'1 is connected to conductor 53, and conductor 32 is connected to the other power line 56. A starting winding 58 is shunted around the motor, one terminal of the winding being connected to power line 55 and the other terminal to conductor 14.

Thus it will be seen that the circuit breaker portion of the control device, including bimetallic strips 25 and 33, are always in series with the motor, and are also in series with the starting winding 58, when the motor draws above current to energize relay coil I l.

The action of the bimetallic strips is as follows: in Fig. l the parts are shown in their normal condition, that is, with a current well within the safe operating limit. When a heavier current goes through the device, both of the bimetallic elements 25 and 33 flex in the same direction. Ihe contact strip 36 is normally biased against the bimetallic element 25 by means of spring 48, but when the bimetallic strip 25 reaches the limit of its movement, as shown in Fig. 4., further movement of the bimetallic strip 33 through the overcenter position will cause the contact strip 36 to move in the opposite direction, thereby opening the circuit between the contact points 55 and 45, and thus opening the motor circuit. It will be seen that this substantially parallel movement of the two bimetallic strips permits of a considerable delay, particularly on small overloads. This delay can be regulated by the adjusting screws 50 and 21. The nature of this delay is such that the additional current imposed on the bimetallic strips by the cut-in of the starting winding 58 may be carried for that length of time which is normally required to bring the motor up to speed.

From the open circuit position shown in Fig.- 5 the parts will return to the normal position, shown in Fig. 1, as the bimetallic strips cool 01f.

As an example of the operation of this control device, the motor 51 can be one which draws 2.8 amperes during normal running conditions. The action of the bimetallic elements 25 and 33 is such that a circuit will be opened in 30 minutes when drawing 3.2 amperes, and within a few seconds, when drawing 13 amperes. The relay opened in a much shorter period of time.

In Figs. 9 and 10 are shown a modified form of circuit breaker which includes a U-shaped bimetallic strip 60 and a centrally disposed resilient contact member ii, which correspond to elements 33 and 36 of Figs. 1 to 5. These are mounted in the same manner as shown in the previous figures, and are provided with an over center spring 69 and a washer 10. In this form of the invention, the additional bimetallic element 25 is omitted, and the delaying action is secured by shorting out one-half of the U shaped bimetallic strip 60. This is efiected by providing a projection on the connecting portion of the U-shaped bimetallic element which serves as a contact 62. A bracket 63 carries a follow-up spring 64 which is provided with a contact point 65 for cooperation with the contact 62. Thus in the position of the parts shown in Fig. 9, which represents the normal running condition of the motor, the lower half of the bimetallic strip 63 is shorted out. However, as the overload approaches a dangerous condition, the bimetallic strip 60 begins to flex away from the bracket 63. The resilient mounting for the contact point 65 permits the circuit to be maintained for a small portion of this movement; however, the circuit between contacts 62 and 65 is eventually broken, thus causing the current to flow through the entire bimetallic strip 60, and greatly accelerating its action.

Further movement of the bimetallic strip causes operation of the overcenter spring 69, thus snapping the resilient contact strip 6! away from its cooperating contact point 68, thereby opening the circuit.

Adjusting screws 55 and 61 may be provided in the bracket 63, and insulated therefrom, which adjusting screws serve to shift the flexing point of the bimetallic strip 60, and thereby permitting regulation of the time delay.

As shown in Fig. 10, suitable conducting means it are provided between the contact point 65 and. the terminal portion 12 of the bimetallic strip 90. Leads 73 and 74 extend from the tor minal portion 12 and contact 68, respectively, to the other portions of the motor circuit.

Figs. 11 and 12 show a still further modification in which the parts are the same as those shown in Figs. 9 and 10, and in which they bear the same reference numerals, with the exception that the adjusting screws 66 and 61 are eliminated. In this modification, however, a separate heating element 15 is provided which is in series with the bimetallic strip so as to provide an additional source of heat for the bimetallic strip, thereby changing its characteristics somewhat. In addition, a strip of copper or like material 16, may be disposed adjacent, the lower portion of the U-shaped bimetallic strip Ell which serves to conduct away whatever heat is conducted into that portion of the strip from the upper portion thereof. As shown, this strip 16 may be a portion of the conducting means II, or it is obvious that the two may be separate if desired.

It is contemplated that these modified forms of the invention be incorporated into the motor control device, including the relay shown in Figs. 1 to 5. In each instance they embody overcenter construction which permits a certain amount of movement on the part of the U- shaped bimetallic strip before the motor circuit is opened, and both the opening and the closing of the motor circuit is efiected by a snap action. In Figs. 1 to 5, the delay is occasioned by the use of two thermostatic elements flexing in the same direction, whereas in Figs. 9 to 12, the delay is. caused by rendering a portion of the single thermostatic element inoperative during the preliminary heating up period. The arrangement is such that the ineffectiveness of the shorting out arrangement is not so noticeable on small overloads of a long period, but the delay is most no= ticeable when a heavier overload is imposed on the motor for a short period of time, such as the load occasioned by the cutting in of a starting winding. The difference in action between small overloads of considerable duration and heavy overloads of short duration is further accentuated by the use of the heating element 15, the shape and nature of which is subject to considerable modification, but a preferred form of which is shown in Fig. 13.

Although only preferred modifications of this invention have been shown and described herein, it is obvious that various modifications and changes may be made therein without departing from the spirit of this invention. The foregoing description and drawings are deemed to be illustrative only and the invention to be limited only by the appended claims.

I claim:

1. In a circuit breaker, two strips mounted side by side, one of said strips being a bimetallic strip, and the other of said strips being a resilient strip, overcenter means connecting the free ends of both, said strips being connected in series circuit with each other and in series with the circuit to be broken, and a cooperating contact disposed adjacent the free end of said resilient strip, a second bimetallic strip mounted for deflection in the same direction as said firstmentioned bimetallic strip and carrying said 00- operating contact, said bimetallic strips being arranged so that a heavier than normal current passing therethrough will cause parallel deflection thereof, and means for limiting the deflection of said second-mentioned bimetallic strip to cause operation of said overcenter means upon further deflection of said first-mentioned bimetallic strip whereby the circuit through said resilient strip will be broken, said overcenter means embodying means to insulate the free ends of said strips from each other.

2. A circuit breaker comprising two strips mounted side by sidein series circuit with each other and in series with the circuit to be broken, one of said strips being a bimetallic element and the other of said strips being a resilient strip, an overcenter spring connecting the free ends thereof. an insulating washer disposed at one end of said spring to insulate said free ends from each other. a cooperating contact adjacent the free end of said resilient contact strip, said cooperating contact and said resilient strip normally being in closed circuit position except during such times as said bimetallic strip is deflected to an extent suflicient to cause operation of said overcenter spring, and a second bimetallic strip mounted for deflection in the same direction as said first-mentioned bimetallic strip, and carrying said cooperating contact.

3. A circuit breaker comprising two strips mounted side by side in series circuit with each other, one of said strips being a bimetallic element and the other of said strips being a resilient strip, an overcenter spring connecting the free ends thereof, a movable contact adjacent the free end of said resilient strip, means to limit the displacement of said movable contact, said movable contact and said resilient strip normally being in closed circuit position except during such times as said bimetallic strip is deflected to an extent suflicient to cause operation of said overcenter spring, and a second bimetallic element mounted for deflection in the same direction as said first mentioned bimetallic strip, and carrying said movable contact.

4. A circuit breaker comprising a U-shaped bimetallic strip, a bracket for mounting the same at its free ends, a resilient contact strip mounted on said bracket between the arms of said U-shaped strip and in series circuit therewith, a second bimetallic strip mounted adjacent said U-shaped bimetallic strip for deflection in the same direction, cooperating contact means carried by said resilient contact strip and said second bimetallic strip for closing a circuit there between, a spring interposed between said resilient contact strip and the closed end of said U-shaped bimetallic strip, and insulated from one of said strips, to bias said resilient contact strip into closed circuit position, and means to block the movement of said second mentioned bimetallic strip beyond a predetermined position whereby further heating of said U-shaped bimetallic strip will cause an overcenter action of said spring resulting in the opening of the circuit between said resilient contact strip and said second mentioned bimetallic strip.

ERNST WALTER RICKMEYER.

REFERENCES CITED The following references are ofrecord in the tile of this patent:

UNITED STATES PATENTS Number Name Date 1,959,205 Hanei May 15, 1934 2,068,374 Carlson Jan. 19, 1937 2,117,123 Werner May 10, 1938 2,175,032 Schaefer Oct. 3, 1939 2,185,517 Pearce Jan. 2, 1940 2,194,999 Clark Mar. 26, 1940 2,284,383 Elmer May 26, 1942 2,302,315 Hall ..-Nov. 17, 1942 2,343,188 Johnson et al. Feb. 29,1944 2,357,770 Runke Sept. 5, 1944 2,379,602 Stickei" July 3, 1945 2,385,001 Jennings Sept. 18, 1945 FOREIGN PATENTS Number Country. Date 594,744 Germany Mar. 21, 1934 

